Drop weight impact damage additive for a surface or component to be tested

Abstract

A system and an associated method for inflicting structural impact damage on an object are disclosed. Certain embodiments of the system comprise: a main support body; a guide tube with a lower end region that can be connected to the main support body and with a hollow inner passage; an adjustable weight assembly that can be received and moved within the hollow inner passage; an impact tip that can be received in an opening formed in a lower end region of the main support body, wherein the impact tip can be moved within the opening such that an exposed length of the impact tip projects from the main support body; and a movement-limiting arrangement associated with the impact tip. The movement-limiting arrangement is adjustable to define a variable maximum penetration depth of the impact tip with respect to the object.

Description

TECHNICAL FIELD

[0001] The embodiments of the subject matter described herein generally relate to structural testing methods and associated testing equipment. More specifically, embodiments of the subject matter relate to a structural testing method for inflicting impact damage on a surface or component under test. BACKGROUND

[0002] Structural testing of materials and components is required in many industries, such as aircraft manufacturing, automotive engineering, and similar fields. One type of structural testing involves damaging a surface or component under test so that the properties and characteristics of the damaged test object can be determined or observed. In this context, a test object can be damaged in a controlled manner by impacting another object, such as a component of a test fixture or system. When impact testing a test object made of (or containing) a composite material, a desired depth range for the inflicted impact damage and a maximum energy that can be applied in producing the impact damage can be specified.

[0003] For this purpose, a conventional drop hammer system can be used for a gravity-based impact testing system. Tests are conducted with a drop hammer system by calibrating the system to determine the correct energy (e.g., a combination of weight and drop height) using a calibrated test specimen and a freely falling weight that causes the desired impact damage depth. Once the appropriate combination of weight and drop height has been determined, the same combination is used with the actual test specimen to achieve the same impact depth. Unfortunately, inconsistencies between composite test specimens can result in deeper or shallower impact damage on the actual test specimen. Such uncontrolled fluctuations in impact damage depth are undesirable and should be avoided wherever possible.

[0004] Accordingly, it is desirable to have an improved methodology and testing system that inflicts impact damage on a test object in a reliable, accurate, and predictable manner. Furthermore, other desirable features and characteristics will become apparent from the following detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background. SHORT SUMMARY

[0005] A system for inflicting structural impact damage to an object is described herein. Embodiments of the system include: a main support body; a guide tube having a lower end portion connectable to the main support body and having a hollow internal passageway; an adjustable weight assembly receivable and movable within the hollow internal passageway; an impact tip receivable within an opening formed in a lower end portion of the main support body, the impact tip movable within the opening such that an exposed length of the impact tip protrudes from the main support body; and a travel limiting assembly associated with the impact tip. The travel limiting assembly is adjustable to define a variable maximum penetration depth of the impact tip relative to the object.

[0006] A method for inflicting structural impact damage to an object is also described herein. Embodiments of the method include: initializing a test system for inflicting impact damage to obtain a target dent depth in a surface of the object. Certain embodiments of the test system comprise: means for impacting an impact tip with a predetermined maximum energy; and means for limiting the travel of the impact tip. The limiting means is adjustable to define a variable maximum penetration depth of the impact tip relative to the surface of the object. The initialization step results in a first maximum penetration depth for the impact tip.The method also comprises: operating the impact means to apply the predetermined maximum energy to the impact tip using the first maximum penetration depth; measuring a resulting dent depth formed in the surface of the article in response to the movement of the impact tip caused by operating the impact means; comparing the resulting dent depth to the desired dent depth; adjusting the limiting device if the resulting dent depth deviates from the desired dent depth by at least a specified tolerance value, wherein the adjusting changes the first maximum penetration depth to a second maximum penetration depth; and after adjusting the limiting device, operating the impact device to apply the specified maximum energy to the impact tip using the second maximum penetration depth.

[0007] This summary is intended to introduce, in simplified form, a selection of concepts described further below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be an aid in determining the scope of the claimed subject matter. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] A more complete understanding of the subject matter will be obtained from the detailed description and claims when considered in conjunction with the following figures, wherein like reference numerals refer to similar elements in the figures. Fig. 1 is a simplified schematic representation of an exemplary embodiment of a system for inflicting structural impact damage to an object; Fig. 2 is a perspective top view of a main support body adapted for use with the Fig. 1 system shown; Fig. 3 is a perspective view of the main support body from below; Fig. 4 is a plan view of the main support body; Fig. 5 is a bottom view of the main support body; Fig. 6 is a side view of the main support body; Fig. 7 is a cross-sectional view of the main support body along the Fig. 4 and Fig. 5 shown section line 7-7; Fig. Figure 8 is a perspective view of a guide tube adapted for use with the Fig. 1 system shown; Fig. 9 is an exploded side view of an adjustable weight assembly suitable for use with the Fig. 1 system shown; Fig. 10 is a front view showing the adjustable weight unit inside the guide tube; Fig. 11 is a simplified cross-sectional view showing some of the Fig. 1 contains the components of the system shown; Fig. 12 is an enlarged cross-sectional view showing some of the components of the Fig. 1 system shown; and Fig. 13 is a flowchart illustrating an exemplary embodiment of a method for inflicting structural impact damage to an object. DETAILED DESCRIPTION

[0009] The following detailed description is merely illustrative and is not intended to limit the embodiments of the subject matter or the application and uses of such embodiments. As used herein, the word "exemplary" means "serving as an example, instance, or illustration." Any implementation described herein as exemplary is not necessarily to be construed as preferred or advantageous over other implementations. Furthermore, there is no intention to be bound by any express or implied theory presented in the foregoing technical field, background, brief summary, or the following detailed description.

[0010] In addition, certain terms in the following description may be used for reference purposes only and are not to be considered limiting. For example, terms such as "top," "bottom," "over," and "under" refer to directions in the drawings to which reference is made. Terms such as "front," "back," "side," "outside," and "inside" describe the orientation and / or location of parts of the component within a consistent, but arbitrary, frame of reference that will become clear by reference to the text and accompanying drawings in which the component in question is described. This terminology may include the words expressly mentioned above, their derivatives, and words of similar import. Also, the terms "first," "second," and other numerical terms referring to structures do not imply order unless clearly indicated by the context.

[0011] This description relates to a method and associated test system for inflicting damage using a drop-weight impact method. In this context, impact damage is a common requirement for fatigue and damage tolerance testing of materials and components used in the manufacture of vehicles, e.g., aircraft.

[0012] In a conventional "drop hammer" system, the objective is to determine the impact energy that will produce a desired dent depth in the surface of the test object. Determining the desired impact energy is accomplished using a calibration routine in which dents are impacted into a calibration or test object that is structurally similar to the impact location of the actual object where the calibrated impact depth is to be created. The desired impact energy is determined by varying the applied impact energy (typically limited by a predetermined maximum amount of energy), measuring the resulting dent depths, and determining the applied impact energy that can repeatedly produce the desired dent depth.After determining the calibrated impact energy, a final impact is applied to a location on the calibrating test piece that is identical (or substantially similar) to the actual damage location on the official test piece. The resulting dent depth is measured to confirm whether the calibrated impact energy produces consistent results. After setting up the official test piece with the same boundary conditions as the calibration setup, the official impact damage is induced at the designated location using the calibrated impact energy. The routine described above can be performed for any official damage location.

[0013] The subject matter presented here represents an improvement over the conventional drop hammer system and method for calibrating and creating impact dents of a specific depth. In contrast to the conventional method, which requires the determination of a specific impact energy, the method described below uses a deflection-limited drop hammer system that applies a specific maximum impact energy for each impact. The impact system includes an impact tip that is struck against the surface of the object to cause impact damage. The system also includes means for limiting the travel of the impact tip, which are adjustable to define a variable maximum penetration depth of the impact tip with respect to the surface of the object.By changing the properties (setting) of the travel limiting device, the displacement of the impact tip caused by the application of the maximum impact energy can be controlled to achieve the target penetration depth. After reaching the target dent depth, a final impact is applied to a location on the calibration test piece that is identical (or substantially similar) to the actual damage location on the official test piece. The resulting dent depth is measured to confirm whether the travel limiting devices are arranged to produce consistent results or not. After setting up the official test piece with the same boundary conditions as the calibration setup, the official impact damage is caused at the intended location using the same system configuration and the specified maximum energy.The routine described above can be performed for any official damage site.

[0014] The system described here produces impact damage without exceeding the specified maximum energy or an experimentally determined dent depth. The deflection-limited drop hammer method provides an impact that meets specific test requirements while increasing accuracy and reducing the risk of unplanned damage to the test specimen.

[0015] Referring to the drawings, Fig. 1 is a simplified schematic representation of an exemplary embodiment of a system 100 for inflicting structural impact damage 102 (e.g., dents, dimples, cracks, stains, dents, or the like) on an object 104. During calibration of the system 100, the object 104 may be considered a "test object" or "calibration object" for the purposes of this description. After calibration of the system 100, the object 104 may be referred to as a "sample object" to distinguish it from the object(s) previously damaged during the calibration routine.

[0016] The illustrated embodiment of the system 100 includes, without limitation: a main support body 108; a guide tube 110 having a lower end portion 112 connectable to the main support body 108; an adjustable weight assembly 114 receivable and movable within the guide tube 110; an impact tip 116 receivable within an opening formed in a lower end portion of the main support body 108; and a travel limiting assembly (in Fig. 1 not visible) connected to the impact tip 116. The travel limiting assembly is adjustable to define a variable maximum penetration depth of the impact tip 116 relative to the object 104. It should be noted that the travel limiting assembly and / or an equivalent structure are exemplary means for limiting the travel of the impact tip 116. In certain embodiments, the system 100 also includes or cooperates with a support structure 120. The support structure 120 is suitably configured and arranged to hold the main support body 108 in a fixed position relative to the object 104. The support structure 120 (and / or a separate support structure not shown) may also be configured and arranged to hold the guide tube 110 in a fixed position relative to the main support body 108. The system 100 may also include a spacer 124 (in Fig. 1 not shown, but in Fig. 11) having a calibrated thickness to initialize a distance between the main support body 108 and the object 104. In certain embodiments, the system 100 also includes or cooperates with a support structure 128 that is suitably configured, arranged, and adjusted to hold, retain, and align the object 104 in a stationary position relative to the main support body 108.

[0017] Fig. 1 shows the support structures 120, 128 in simplified schematic form. In practice, the support structures 120, 128 may comprise or be implemented as any number of the following elements, individually or in any suitable combination: at least one scaffold, at least one support rail or support beam, at least one floor frame, at least one pedestal or platform, at least one shim or spacer, at least one clamp, at least one strap or band, a stabilizing or damping mat or material, a truss system, or the like. In accordance with certain embodiments, the support structure 120 utilizes a scaffold support structure 132 and one or more horizontal beams 134.At least one of the horizontal supports 134 is connected to the main support body 108 to hold it in position, and at least one of the horizontal supports 134 is connected to the guide tube 110 to hold it in position. The horizontal supports 134 can be connected to the main support body 108 and the guide tube 110 using any suitable mechanism, device, fastener, or tool (e.g., clamps, bolts, screws, or clamps). In accordance with certain embodiments, the support structure 128 includes components or material that support the underside of the article 104 at the desired height and orientation.The support structure 128 may also include or cooperate with one or more fixtures or tools, lifting devices or lifting mechanisms, weights (connected to or resting on the top of the object 104), and / or other components that hold the object 104 in the desired position during the impact test. The two support structures 120, 128 can be initialized and adjusted as needed to maintain the main support body 108 in a fixed position relative to the target position on the exposed surface of the object 104. Between repetitions of the impact test, the support structure 120 and / or the support structure 128 can be moved, adjusted, or repositioned as needed to reorient the impact tip 116.

[0018] The Fig. show various views of an exemplary embodiment of the main support body 108. More specifically: Fig. 2 is a perspective view from above; Fig. 3 is a perspective view from below; Fig. 4 is a top view; Fig. 5 is a bottom view; Fig. 6 is a side view; and Fig. 7 is a cross-sectional view from the perspective of section line 7-7, which is shown in Fig. 4 and Fig. 5. The main support body 108 may be made of any suitably tough, strong, and rigid material, such as steel or aluminum. In certain embodiments, the main support body 108 is a one-piece component machined from a solid stock or otherwise manufactured as a unitary component.

[0019] The illustrated embodiment of the main support body 108 is characterized, without limitation, by the following features: an upper end portion 202; a lower end portion 204; a tube opening 206 formed in the upper end portion 202; a tip opening 208 formed in the lower end portion 204; and mounting flanges 210. As described in more detail below, certain features and characteristics of the main support body 108 are designed and configured to accommodate the guide tube 110, the impact tip 116, and the means for limiting the travel of the impact tip.

[0020] The tube opening 206 begins at an upper surface 214 of the main support body 108, extends through a portion of the main support body 108, and terminates within the main support body 108 at or near the lower end portion 204 (see Fig. 7). The tube opening 206 is shaped and sized to be compatible with the guide tube 110. According to the illustrated embodiment, the guide tube 110 and the tube opening 206 are cylindrical, and the guide tube 110 is sized to be removably connected to the main support body 108 if necessary. The guide tube 110 can be secured in the tube opening 206 with at least one set screw received in a threaded hole 218 (see Fig. 3, Fig. 6 and Fig. 7), with a suitably designed fitting or connector, via a threaded engagement with the pipe opening 206 or the like.

[0021] According to the illustrated embodiment, the lower end of the tube opening 206 is connected to a strip 216 formed within the lower end portion 204. The strip 216 is in the Fig. The bar 216 serves as a base or platform for limiting the insertion depth of the guide tube 110 into the main support body 108. In this context, the lower end of the guide tube 110 may rest against the bar 216, as shown in the Fig. shown.

[0022] In certain embodiments, a spacer cavity 222 is formed in the lower end portion 204 of the main support body 108. The spacer cavity 222 is in Fig. 4 and Fig. 7; the spacer cavity 222 is shown in Fig. 11 and Fig. 12. As shown in Fig. 7, the upper portion of the spacer cavity 222 terminates at least with a portion of the lower end of the tube opening 206. The spacer cavity 222 terminates at a base surface 224 defined within the lower end portion 204. The top surface of the tip opening 208 is connected to at least a portion of the spacer cavity 222. As shown in Fig. 7, the tip opening 208 extends between the lower end of the spacer cavity 222 and a lower end surface 228 of the main support body 108 such that the tip opening 208 is accessible from the underside of the main support body 108.

[0023] The illustrated embodiment of the main support body 108 includes mounting flanges 210 and / or other features that enable the main support body 108 to be attached to the support structure 120. For example, the mounting flanges 210 may be positioned to rest on one or more of the horizontal beams 134 to prevent movement of the main support body 108 during impact testing. The mounting flanges 210 may also be configured to accommodate coupling devices or elements such as clamps, fittings, fasteners, connectors, locks, or the like.

[0024] The guide tube 110 is compatible with the main support body 108 and can be removably connected to the main support body 108 if necessary to support the impact testing method presented here. Fig. 8 is a perspective view of an exemplary embodiment of the guide tube 110. For reasons of space, Fig. 8, the guide tube 110 is shown in an arbitrarily split form, with an intermediate section removed. The guide tube 110 includes an upper end portion 302, a lower end portion 304 terminating in an opening 306, a hollow interior passage 308 (in Fig. 11) and a longitudinal slot 310 formed in a side wall 312 of the guide tube 110. The illustrated embodiment of the guide tube 110 also includes a mounting structure 314.

[0025] The lower end portion 304 of the guide tube 110 fits into the tube opening 206 of the main support body 108 and can be secured in position during the impact test. The hollow inner passage 308 accommodates the adjustable weight assembly 114, as described above with reference to Fig. 1. The adjustable weight assembly 114 is slidable within the hollow inner passage 308 so that it can be raised to a desired initial height and released to fall toward the lower end portion 304 during the impact test. When the guide tube 110 is coupled to the main support body 108, the lower end surface of the guide tube 110 rests against the bar 216 (see Fig. 11 and Fig. 12). When the guide tube 110 is installed in this manner, the opening 306 provides access (from above) to the impact tip 116.

[0026] Fig. 9 is an exploded side view of an exemplary embodiment of the adjustable weight assembly 114. The illustrated embodiment of the adjustable weight assembly 114 includes, without limitation: at least one weight 402; a hammer head component 404; and a handle 406. In certain embodiments, the adjustable weight assembly 114 includes a plurality of individual weights 402 that are coupled and combined together to provide a particular drop weight to be used during an impact test. Fig. Figure 9 shows two weights 402a, 402b, but the dashed line between the two weights 402 indicates that any number of additional weights 402 can be added to obtain the desired drop weight. In an alternative embodiment, the adjustable weight assembly 114 uses only one weight 402, which can be selected from a set or assortment of available weights. A non-limiting example is that the weights 402 are made of a heavy and durable material such as brass and that they can be connected to each other via a threaded engagement, fasteners, threaded inserts, or the like.

[0027] The hammer head component 404 may be a removable component (as in Fig. 9) or it may be attached to or integrated with the lowermost weight 402 of the adjustable weight assembly 114. In some embodiments, the hammer head component 404 is connected to a weight 402 via a threaded engagement. The hammer head component 404 is preferably made of a robust and durable material such as brass, steel, iron, or the like. The hammer head component 404 includes a striking surface 410 configured and arranged to impact the upper end of the striking tip 116 when the adjustable weight assembly 114 is released to fall within the guide tube 110 (this operation is described below with reference to the Fig. described in more detail). The handle 406 is removably coupled or attached to a weight 402 to facilitate raising the adjustable weight assembly 114 to an initial height within the hollow passage 308 of the guide tube 110. The weight of the handle 406 is taken into account in the calibration or configuration of the adjustable weight unit 114. As in Fig. 10, the longitudinal slot 310 receives a portion of the handle 406 to allow the handle 406 to move up and down as the adjustable weight unit 114 moves within the hollow inner passage 308.

[0028] As in Fig. 11 and Fig. 12, an upper end 420 of the striking tip 116 is accessible via the opening 306 of the guide tube 110 (when the guide tube 110 is connected to the main support body 108). Thus, the adjustable weight assembly 114 strikes the upper end 420 of the striking tip 116 when the adjustable weight assembly 114 is released to fall within the guide tube 110 (as shown in Fig. 11). In the embodiment described here, the striking surface 410 of the hammer head component 404 strikes the upper end 420 of the striking tip 116, which in turn strikes the lower end 422 of the striking tip 116 against the surface of the object.

[0029] It should be appreciated that the adjustable weight assembly 114 (which may include one or more weights 402, the hammerhead component 404, and the handle 406) represents an exemplary means for impacting the impactor tip 116 with a specific amount of energy, e.g., a predetermined maximum energy. Alternatively or additionally, the system 100 may include or cooperate with other components, devices, or subsystems that serve as a means for impacting the impactor tip 116. The means for impact may include, for example, a pneumatically actuated element, a spring-loaded element, a projectile, a pendulum impactor, or the like.

[0030] With reference to the Fig. The impact tip 116 is movable within the tip opening 208 of the main support body 108 such that an exposed length of the impact tip 116 protrudes from the main support body 108 during the impact test. In certain embodiments, the impact tip 116 is located unobstructed within the tip opening 208 so that it can move freely. The impact tip 116 may be substantially cylindrical in shape and have a rounded portion forming its lower end 422. The outer diameter of the impact tip 116 is slightly smaller than the inner diameter of the tip opening 208.

[0031] Regarding the Fig. In the exemplary embodiment, the spacer cavity 222 and at least one spacer 502 are used as a movement-limiting assembly for the impact tip 116. In Fig. 11 shows a configuration in which only one spacer 502 is used. In contrast, in Fig. 12 illustrates another configuration in which the movement limiting arrangement comprises a plurality of stackable spacers 502. Although this is not always required, in the example of Fig. 12, three stackable spacers 502 are used, which together define a total height of the spacer. The respective spacer height is selected to regulate the portion of the impact tip 116 that is exposed above the spacer(s) 502 prior to impact (see Fig. 11 and Fig. 12, both of which show the initial state of the impact tip 116 prior to impact, with a portion of the impact tip 116 extending beyond the uppermost surface of the spacer(s) 502. A hole is formed in each spacer 502 to allow the passage and translation of the impact tip 116 during use. To this end, each spacer 502 can be implemented as a rigid ring- or donut-shaped disc or washer with a specific or predetermined thickness. The number of spacers 502 and the thickness of each spacer 502 can be selected to achieve the desired overall height. In certain non-limiting embodiments, the thickness of the spacers 502 ranges from about 0.05 inches (0.127 cm) to about 0.30 inches (0.762 cm), providing flexibility in creating various spacer stacks to achieve the desired overall height.

[0032] In the embodiment described herein, the travel-limiting assembly (e.g., selectable spacers with varying spacer thicknesses) is configured to define a plurality of discrete maximum penetration depths of the impact tip 116 relative to the surface 504 of the object 104. A shorter overall spacer height results in a deeper maximum penetration depth, and a larger overall spacer height results in a shallower maximum penetration depth because the top surface of the spacer 502 (or stack of spacers 502) serves as a physical stop that limits the range of downward travel of the adjustable weight assembly 114. More specifically, the top surface of the spacer 502 (or stack of spacers 502) defines the limit of travel of the striking surface 410 of the hammer head component 404.

[0033] The Fig. The combination of three spacers (502a, 502b, and 502c) shown in Figure 12 results in a relatively low maximum penetration depth, as indicated by the shortest double-headed arrow. Using only spacer 502c results in a relatively deep maximum penetration depth, as indicated by the longest double-headed arrow. Using spacer 502b in combination with spacer 502c results in a relatively medium maximum penetration depth, as indicated by the medium-length double-headed arrow. The defined maximum penetration depth corresponds to the length of the impact tip 116 extending beyond the uppermost surface of the spacer(s) 502 when the system is in an initial pre-impact state, as shown in Fig. 11 and Fig. 12 (with the lower end 422 of the impact tip 116 resting on the surface of the object 104 to be impacted).

[0034] It should be noted that the spacer cavity 222, the corresponding structure of the main support body 108, and the spacer(s) 502 represent an exemplary means for limiting the travel of the impact tip 116, which is adjustable to define a variable maximum penetration depth of the impact tip 116 relative to the surface 504 of the article 104. Alternatively or additionally, the system 100 may include or cooperate with other components, devices, or subsystems that serve as a means for limiting the travel of the impact tip 116.For example, the means for limiting travel may include, or be implemented as, without limitation, any of the following: a movable platform or base having an adjustable height; one or more threaded members (similar to a bolt or screw) that can be adjusted to extend to a specific height within the spacer cavity 222; removable or adjustable pins or rods extending laterally into the spacer cavity 222, wherein the installed height of such pins or rods can be selected to limit the movement of the impact tip 116; removable or adjustable pins or rods extending laterally into the hollow interior passageway 308, wherein the installed height of such pins or rods can be selected to limit the movement of the adjustable weight assembly 114.

[0035] Fig. Figure 11 shows the main support body 108 in an initial position relative to the object 104 to be impacted. In the initial position, the main support body 108 is held in a fixed position with a defined distance between the lower end surface of the main support body 108 and the upper surface of the object 104. The impact tip 116 protrudes through the tip opening 208 and rests on the upper surface of the object 104. For the reasons explained above, it is important to maintain this desired distance, as the defined distance influences the maximum penetration depth of the impact tip 116. Accordingly, in the illustrated embodiment, the spacer 124 is used to initialize the distance between the lower end surface of the main support body 108 and the object 104. The spacer 124 also serves as a guide to ensure that the impact tip 116 is perpendicular to the target surface of the object.When the system is set up, the bottom of the main support body 108 rests against the top of the spacer 124. The orientation of the main support body 108 can be adjusted as needed (e.g., using shims) to compensate for situations where the target surface is not exactly parallel to the ground.

[0036] The spacer 124 has a calibrated thickness corresponding to the desired spacing, which thickness affects the maximum dent depth that can be created by the impact tip 116. In certain non-limiting embodiments, the spacer 124 has a thickness in the range of about 0.125 inches (0.3175 cm) to about 0.8 inches (2.032 cm). The spacer 124 may have an opening 510 (e.g., a slot, hole, or cutout) formed therein to receive a protruding portion of the impact tip 116 extending from the lower end surface of the main support body 108. In certain embodiments, the opening 510 is configured as a slot extending from an edge of the spacer 124. The slot configuration allows the spacer 124 to be positioned during initialization, as shown in Fig. 11, and then removed (without having to remove the impact tip 116 from the main support body 108) before performing the impact test. Fig. 12 shows the main support body 108 and the striking tip 116 in the starting position after removal of the spacer 124.

[0037] The system 100 described above or an equivalent implementation or embodiment thereof can be used to perform structural impact tests on various objects. In this context, Fig. 13 is a flowchart showing an exemplary embodiment of a process 600 for inflicting structural impact damage to an object. For illustrative purposes, the following description of the process 600 may refer to elements discussed above in connection with the Fig. 1-12. In practice, parts of the process 600 may be performed by various elements of the described system. It should be noted that the method 600 may include any number of additional or alternative steps, that the Fig. 13 need not be performed in the order shown, and that the method 600 may be integrated into a more comprehensive method or process with additional functionality not described in detail here. In addition, one or more of the steps shown in Fig. 6 may be omitted in one embodiment of the method 600 as long as the intended overall functionality is maintained.

[0038] The described implementation of method 600 provides for any number of iterations designed to calibrate the impact damage infliction testing system using a test article that is similar, equivalent, or identical to a master article under test. One or more calibration iterations are performed on a "training zone" of the test article until impact damage with a specified dent depth is observed. In accordance with typical testing procedures, the training zone is at least two inches (5.08 cm) from the actual target of the test article. After the specified dent depth is measured in the training zone, a confirmation impact is applied to the actual target of the test article (located at the same or a structurally equivalent location on the test article).Once the specified dent depth is confirmed at the intended target, the calibrated test system can be used to create the same type of impact damage at the desired target location on the specimen. Proper calibration and adjustment of the test system ensures that the specimen sustains impact damage with the desired dent depth.

[0039] The illustrated embodiment of method 600 begins with obtaining the required system configuration and test data (step 602). The data obtained in step 602 may vary depending on various factors and considerations, including, but not limited to: the particular test method, requirements, objectives, and / or conditions; the design or configuration of the article(s) to be tested; the material(s), composition, or mechanical properties of the article(s) to be tested; the environmental conditions; or the like. In accordance with certain embodiments, the data obtained in step 602 may include, without limitation, a specified or maximum impact energy (E MAX ) to be used during the impact test; the target dent depth (d T) to be formed in the surface of the article under test; the length of the impact tip (the particular length may be selected as needed for the particular application and configuration of the article); the height of the spacer used to initialize the system; and an initial configuration, setting, or dimension of the means for limiting the travel of the impact tip. For the example described above, where the limiting device accommodates stackable spacers, an initial spacer height may be specified at step 602. For example, an initial spacer height of zero may be specified so that the first iteration of the impact test is performed without internal spacers, resulting in the greatest allowable penetration depth of the impact tip.Alternatively, a non-zero initial spacer height can be specified, so that the first iteration of the impact test is performed with at least one internal spacer. In practice, the goal of the first impact iteration is to obtain a dent deeper than the target dent depth, so that the system can be calibrated with subsequent impact iterations resulting in shallower dent depths (until the target dent depth is reached). T is reached).

[0040] The test system is initialized (step 604) in accordance with at least some of the data obtained in step 602. Initialization prepares the test system to achieve the predetermined target dent depth in the exposed surface of the test object. In certain embodiments, the test system is initialized by configuring the adjustable weight assembly to obtain a calibrated weight or mass. Based on the calibrated weight and the specified value of E MAXA calibrated height can also be calculated. Accordingly, the calibrated weight assembly is raised to the calibrated height from which it is released. During initialization, the test system can also be configured to provide the initial height of the spacer, install the impact tip, and adjust the positions of the main support body and the test object so that the spacer is in place and the end of the impact tip rests on the surface of the test object (see Fig. 11). The position of the test object can be adjusted as needed—e.g., using washers, adjusters, blocks, or spacers—so that the guide tube is perpendicular to the surface of the object at the point of impact. As explained above, initializing the test system with the initial spacer height results in an initial maximum penetration depth for the impact tip. After fixing the position of the main support body relative to the test object, the spacer can be removed.

[0041] After initializing the test system, the method 600 continues by performing an impact repetition at a target location within the test article's training zone using the specified E MAX is carried out (step 606). In this context, the impact means (e.g., the weight arrangement) is operated so that the specified E MAXis applied to the impact tip using the initial maximum penetration depth configuration. In the exemplary embodiment, step 606 is performed by releasing the calibrated weight assembly from its calibrated height, causing the weight assembly to impact the top of the impact tip. The weight assembly can be manually raised to the desired height (the guide tube may include or cooperate with appropriate measurement markings, a height scale, a ruler, or a tape measure), held in place, and manually released at the appropriate time.In some embodiments, the weight assembly may be raised to the desired height and held in place by a suitably configured locking mechanism, lock, lever, one or more support pins or plates or arms, an operable door or shelf, or the like - and thereafter released by actuating, activating, or otherwise manipulating the device, component, or element holding it in place.

[0042] Thereafter, the method 600 continues by measuring the resulting dent depth (if any) that forms in the surface of the test piece in response to the movement of the impact tip caused by the impact (step 608). Measuring the dent depth may require removal or movement of the test piece and / or removal or movement of the main support body of the testing system. In addition, it may be necessary to lift or remove the weight unit from the impact tip. A depth gauge with suitable accuracy, precision, and measurement tolerance may be employed or used for step 608. In this example, it is assumed that the first impact repetition produces a measurable dent. A scenario in which the first impact repetition does not produce a measurable dent is described below.

[0043] The method 600 continues by determining the resulting dent depth (di ) with the target dent depth d T is compared. In Fig. 13, the subscript letter "i" is used to indicate the current impact iteration. In the illustrated version of method 600, a check is carried out to determine whether the resulting dent depth is at least a specified tolerance value greater than the target dent depth (query step 610). If d i > d T (Branch "Y" of query step 610), the test system is adjusted for the next impact iteration to produce a shallower impact dent. More specifically, the limiting means can be adjusted to change the first maximum penetration depth to a new maximum penetration depth. For the scenario where the resulting dent depth is deeper than the target dent depth, method 600 adjusts the limiting means so that the second maximum penetration depth is shallower than the first maximum penetration depth. Step 612 in Fig. 13 provides for an adjustment of the limiting means, which includes an increase in the overall height of the spacer for the next impact iteration: H i+1 = H i + (d i - d T ). In this relationship, H represents the total height of one or more spacers used to determine the maximum penetration depth, H i is the total height of the spacer for the current impact iteration and H i+1 is the total spacer height for the next impact iteration. According to this relationship, the total spacer height for the next impact iteration is increased by an amount equal to the difference between the measured penetration depth for the current impact iteration and the desired target penetration depth (plus or minus any practical tolerances associated with the available range of spacers).

[0044] After increasing the overall height of the spacer (step 612), the method 600 may return to step 604 to reinitialize the test system and perform the next impact repetition with the same impact energy (E MAX). Reinitializing the test system may include, among other things, repositioning the main support body and / or the test article to target an undamaged location within the test article's exercise zone and raising the weight assembly to the prescribed height. Thus, method 600 may change the position of the test article relative to the test system to expose an undamaged target location with similar support structure on the surface of the test article. The presence of a similar support structure (or similar internal layout) is particularly important when the article is a composite component and / or assembly made of different materials, e.g., a test article with spars, air gaps, or discontinuities below the target surface. Thereafter, the impact process may be repeated to strike the impact tip against the undamaged target location.The next impact iteration will be with the same E. MAX , but with a different maximum penetration depth corresponding to the larger overall height of the spacer.

[0045] If th i is not greater than d T (the “N” branch of query step 610), the method 600 continues by checking whether the i is at least a certain tolerance value smaller than d T (Query step 614). If the i < d T(the "Y" branch of query step 614), the test system is adjusted for the next impact iteration to produce a deeper impact dent. More specifically, the limiting means may be adjusted to change the first maximum penetration depth to a deeper maximum penetration depth. For the scenario where the resulting dent depth is less than the target dent depth, method 600 adjusts the limiting means so that the second maximum penetration depth is deeper than the first maximum penetration depth. Step 616 in Fig. 13 provides for an adjustment of the limiting means, which includes a reduction of the overall height of the spacer for the next impact iteration: H i+1 = H i - (d T - d i). According to this relationship, the total spacer height for the next impact iteration is reduced by an amount equal to the difference between the target dent depth and the measured dent depth for the current impact iteration (plus or minus any practical tolerance related to the available range of spacers).

[0046] After reducing the overall height of the spacer (step 616), the method 600 may return to step 604 to reinitialize the test system and determine the next impact energy (E MAX ). As already mentioned, the impact procedure can be repeated to strike the impact tip against an undamaged target within the training zone of the test object. The next impact repetition is carried out with the same E MAX and the adjusted maximum penetration depth, which corresponds to the reduced overall height of the spacer.

[0047] At 618, the method 600 has determined that the currently measured dent depth (d i ) within a defined measuring tolerance equal to the desired target dent depth (d T ). In response to such a finding, the impact test with the same E MAX repeated to check consistency (step 620). In particular, the method 600 may be continued by changing the position of the test object relative to the test system to expose an undamaged target location on the surface of the test object that corresponds to the actual intended target of the test object. As previously mentioned, the confirmation target location is located outside the test object's training zone. After repositioning the system, the impact process is repeated with the same E MAXand repeated with the same depth-limiting configuration to determine the calibrated maximum penetration depth for the impact tip. In other words, the same test setup and impact application procedure are used to create a confirmation dent at the new target location.

[0048] The method 600 may continue by confirming whether the depth of the confirmation dent (d C ) with the target dent depth (d T ) matches or not. In Fig. 13, query step 622 checks whether the measured depth of the confirmation dent is equal (within a defined measurement tolerance) to the target dent depth. If dc = d T(the "Y" branch of query step 622), then it is assumed that the desired impact damage has been created at the intended target location with the current total height of the spacer (step 624). Thereafter, the test article can be replaced with the desired sample article, the test system can be initialized and otherwise prepared to deliver an impact, and the test system can be operated as described above. The test system is operated so that the impact tip is at E MAXwhich in turn creates a dent on the surface of the test specimen. Calibration of the testing system ensures that the desired dent depth is achieved on the test object. If the measured depth of the confirmation dent deviates from the target dent (the "N" branch of query step 622), the method 600 may return to query step 610 to adjust the height of the spacer(s) if necessary for another impact iteration and recalibrate the system, again referring to query step 622.

[0049] The method 600 provides any number of repeated impact iterations using one or more test pieces to achieve a repeatable impact that produces the desired target dent depth. When the target dent depth is achieved with the maximum applied energy E MAXcannot be achieved, the test point requirements must be reassessed to change either the energy or the target location. For example, the weight assembly can be moved to a higher starting position before release and / or an additional weight can be added to increase the total energy. If the test specifications or requirements do not allow an increase in the maximum impact energy, an alternative impact test point or other solution can be considered.

[0050] The above description of method 600 assumes that the first impact pass results in a measurable dent on the surface of the test piece. However, in certain scenarios, the first impact may leave the surface undamaged or only slightly disfigured without creating a measurable dent. In this context, it is possible that the material is so hard that the maximum applied energy produces no dent or only a very small dent. In this case, the impact surface contacts the top of the impact tip but never the top of the spacer(s). In this situation, the focus shifts from achieving the correct dent depth to ensuring the safety of the test piece (e.g., ensuring that the actual test piece is not damaged if there is an unknown difference between the two targets).Accordingly, it may be desirable to increase the spacer stack height to limit the impact tip travel. Under ideal conditions with a uniformly hard surface, spacers would be unnecessary, as the impact tip can never travel far enough. However, due to the extent of damage associated with removing an impact tip embedded in the object's surface, a spacer height can provide a safety margin. One or more confirmation strikes can be performed with increasing spacer height to observe whether or not a measurable dent is produced at a different target location.

[0051] The above description of method 600 refers to a method in which the height of the spacer(s) can be increased or decreased between impact iterations to change the resulting dent depth. However, in certain scenarios, there may be no measurable difference in the measured dent depth from one impact iteration to the next. In this case, the height of the spacer(s) can be increased slightly before one or more confirmation impacts are performed. As explained in the previous paragraph, increasing the spacers is a safety measure to reduce the risk of damage to the article.

[0052] Although at least one exemplary embodiment has been presented in the foregoing detailed description, it should be understood that numerous variations exist. It should also be appreciated that the exemplary embodiment(s) described herein are not intended to limit the scope, applicability, or configuration of the claimed subject matter in any way. Rather, the foregoing detailed description is intended to provide one skilled in the art with a convenient guide for practicing the described embodiment or embodiments. It is to be understood that various changes in the function and arrangement of elements may be made without departing from the scope defined by the claims, which include known and foreseeable equivalents at the time of filing this patent application.

Claims

[1] A system for inflicting structural impact damage to an object, the system comprising: a main support body; a guide tube having a lower end portion connectable to the main support body and having a hollow internal passage; an adjustable weight assembly that can be received and moved within the hollow inner passage; an impact tip receivable in an opening formed in a lower end portion of the main support body, the impact tip being movable in the opening such that an exposed length of the impact tip protrudes from the main support body; and a movement limiting arrangement associated with the impact tip, the movement limiting arrangement being adjustable to define a variable maximum penetration depth of the impact tip with respect to the object. [2] The system of claim 1, wherein the adjustable weight assembly includes a hammer head component having a striking surface for striking an upper end of the striking tip when the adjustable weight assembly is released to fall within the guide tube. [3] The system of claim 1, wherein the adjustable weight arrangement comprises a plurality of weights coupled together and combined to provide a predetermined drop weight. [4] The system of claim 1, wherein: the lower end of the guide tube ends in an opening; an upper end of the impact tip is accessible through the opening when the guide tube is connected to the main support body; and the adjustable weight unit strikes the upper end of the impact tip when the adjustable weight unit is released and falls into the guide tube. [5] The system of claim 1, wherein the travel limiting assembly is configured to define a plurality of discrete maximum penetration depths of the impact tip with respect to the article. [6] The system of claim 5, wherein the movement limiting assembly comprises a spacer having a hole formed therein to allow passage and translation of the striking tip during use. [7] The system of claim 5, wherein the movement limiting assembly comprises a plurality of stackable spacers, each having a hole formed therein to allow passage and translation of the impact tip during use. [8] The system of claim 1, further comprising a support structure configured to maintain the main support body in a fixed position relative to the article. [9] The system of claim 8, wherein the support structure is configured to hold the guide tube in a fixed position relative to the main support body. [10] The system of claim 1, wherein the adjustable weight assembly includes a handle to facilitate raising the adjustable weight assembly to an initial height within the hollow interior passage of the guide tube. [11] The system of claim 1, further comprising a spacer having a calibrated thickness to initialize a distance between a lower end surface of the main support body and the article, the spacer having an opening formed therein to receive a protruding portion of the impact tip extending from the lower end surface of the main support body. [12] A method of inflicting structural impact damage to an object, the method comprising: Initializing an impact damage infliction testing system to obtain a target dent depth in a surface of the article, the testing system comprising: Means for striking an impact tip with a certain maximum energy; and means for limiting the travel of the impact tip, wherein the limiting means is adjustable to define a variable maximum penetration depth of the impact tip relative to the surface of the object, and wherein the initialization results in a first maximum penetration depth for the impact tip; Actuating the impact means to apply the specified maximum energy to the impact tip using the first maximum penetration depth; Measuring a resulting dent depth formed in the surface of the article in response to the movement of the striking tip caused by the actuation of the striking means; Comparison of the resulting dent depth with the target dent depth; Adjusting the limiting means when the resulting dent depth deviates from the target dent depth by at least a certain tolerance value, wherein the adjustment changes the first maximum penetration depth to a second maximum penetration depth; and after adjusting the limiting means, actuate the impact means so as to transmit the specified maximum energy to the impact tip, using the second maximum penetration depth. [13] The method of claim 12 further comprising: Changing the position of the object relative to the inspection system to expose an undamaged target location on the surface of the object; wherein actuation of the means for impacting using the second maximum penetration depth impacts the impact tip against the undamaged target site. [14] The method of claim 12, wherein, if the resulting dent depth is less than the desired dent depth, the adjusting step adjusts the limiting means such that the second maximum penetration depth is deeper than the first maximum penetration depth. [15] The method of claim 12, wherein, if the resulting dent depth is deeper than the desired dent depth, the adjusting step adjusts the limiting means such that the second maximum penetration depth is less than the first maximum penetration depth. [16] The method of claim 12, wherein if the resulting dent depth deviates from the target dent depth by less than the specified tolerance value, the method further comprises: Changing the position of the object relative to the inspection system to expose an undamaged target location on the surface of the object; Repeating the operation of the impact means to apply the specified maximum energy to the impact tip, using the first maximum penetration depth for the impact tip, to produce a confirmation dent at the target location; and Confirmation whether the depth of the confirmation dent matches the target dent depth. [17] The method of claim 16, wherein, when the confirming step confirms that the depth of the confirmation dent matches the target dent depth, the method further comprises: Replacing the item with a sample item; and Repeating the operation of the impact means to apply the specified maximum energy to the impact tip, using the first maximum penetration depth for the impact tip to create a dent on a surface of the sample article. [18] The method of claim 12, wherein operating the means for striking comprises: Releasing an adjustable weight assembly from a calibrated height to strike the impact point, wherein a calibrated weight of the adjustable weight assembly and the calibrated height are selected to provide the specified maximum energy. [19] The method of claim 18, wherein the initializing step comprises: Configuring the adjustable weight arrangement to obtain the calibrated weight; and Calculate the calibrated height based on the calibrated weight.

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